Kang had initially planned to travel to Washington on Friday for a meeting with Tillerson to discuss the recent breakthrough with North Korea which will hold summits with the South and the United States in the coming months.

The two top diplomats were expected to discuss Seoul and Washington's alliance and cooperation on handling the North Korea nuclear crisis as well as preparations for the upcoming talks.

Amid concerns that Tillerson's exit may cause a setback in coordinating the two countries' policies on North Korea, Kang said the reshuffle would not affect bilateral cooperation.

"This is an abrupt change," she said. "[But] we have worked closely [with the U.S.] and I think we will continue to closely cooperate with the new state secretary as well."

Kang also said it is not appropriate for her to comment on another government's change of personnel.

Trump's new Secretary of State-designate Mike Pompeo is expected to play a key role in preparations for the summit slated for May.

The incumbent CIA director has shown a hard-line stance on the North Korean regime in the past.

"He [Kim Jong Un] can't conduct nuclear testing, he's got to stop the missile testing that he's been hard at for the last years. He's got to continue to allow us to perform our militarily-necessary exercises on the peninsula, and then he's got to make sure that he leaves on the table that discussion for denuclearization," he said in an interview with Fox News Sunday.

Trump said Tuesday that he and Pompeo are "always on the same wavelength," while explaining his decision to dismiss Tillerson in a press conference at the White House.

He said he and his outgoing secretary have long disagreed over major foreign policy issues including North Korea.